6l6gc or 5881 tubes for SLO


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Ok, I know this would normally go in teh tech section, but figured not too many Soldano users would chekc over there and I know tubes cats check out here, so any opinions or thoughts are welcomed.
I have a HotRod100+ I tubed with JJ 6l6gc's and have it tweaked right in, sounding damn near perfect.
I picked up a used SLO today with the Ruby 5881's in it. I know, two different amps. The SLO is already smoother and fatter than the HR100.

My question, I want to retube the SLO. If I throw in 6l6GC, wouldn't it make it fatter and rounder on the lows? So two-fold ? here...
(let's talk new production first)

6l6gc compared to 5881. What differences? Imagine I would choose between JJ (what I usually use), TAD (if they even make them?), and the Tung Sol. What are the actual differences in tone genenrally between 6l6gc and 5881?

Then between the new production actual companies (TS, JJ, TAD)?

What about NOS like the JAN Philips 6l6wgb? Not good to handle the hooter pv on the Soldano stuff?

Liek i say, it is currently sounding better than my HR tweake din with choice preamp tubes, etc! So if I cna get it even better, wow! Creamier and I always love lows and smooth highs. Mainly Hard Blues, lots of classic Rock.
Thanks for any help!


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i tubed my slo with kt66 chinese, and it definitely gives the low end a push.

recently changed back to the 5881 and immediately had to readjust the eq to increase the bass and bump up the depth.

does yours have a depth knob?:dude


Gold Supporting Member
No mods ont his one. I don't really think I'd need the depth one, but the clean scoop might be nice.
So, ....


Hey Scott, the SLO is one of my fav amps of all time...I just love it and the only reason I sold mine is becuase i bought the SLO's more sophisticated brother: the X99.

When I had my SLO, I found the stock Sovtek 5581's sounded best...and I'm a tube hound with a picky ear...but truly after experimenting with lots of preamp and power amp tubes, I think Mike Soldano got it right with the OEM tubes.

That said, the SLO was originally designed around the Phillips 6L6GC's but they arent around any more...if you can find a quad, get your wallet out and fork over a lot of money. I had always wanted to try a quad of them in my SLO, but never did find any and then I sold the amp.

I did find that different tubes do make a difference in the voicing/EQ of the amp, but again, I found the stock SLO with OEM tubes to be close to perfect...as a bonus, they're really cheap and they're durable as hell. I say all that with this caveat though: I find the SLO to be about the most perfectly EQ'd amp on the planet and I don't find the SLO to be lacking in the low end department...I just don't get the criticism of the SLO not having low end...in fact, I had to reduce my bass to about 11:00...but, I also played it with the volume output above 2:00 and that's key for getting the really world-class tones from the SLO.

Its a loud beast of an amp, but one of the best and truly a classic now...enjoy it and congrats on a great amp.

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